HSV-1 and HSV-2 clinical isolates were kindly provided by Dr.
María Oña (Virology Department, Asturias Central Hospital). Both
herpes viruses were propagated in green monkey kidney (Vero)
cells (ECACC No. 84113001) and titrated by microscopical visualisation
of cytopathic effect (CPE), using the endpoint dilution
method described by Reed and Muench (1938). Vero cells were
grown in Dulbecco modified Eagle’s essential minimal medium
(DMEM) supplied with 10% foetal bovine serum. Cells were maintained
in DMEM with serum concentration reduced to 2%.